Like anyone who works with painting, design or color in any form, I occasionally struggle with color; not just with mixing and choosing colors, but with the actual perception of color, the ability to answer the seemingly simple question “What color is that?”

All of my studies of color and color theory have led me to the inexorable conclusion that the single most important rule of color is that the human perception of any color is almost entirely dependent on adjacent or surrounding colors.

This is the basis of Eugene Delacroix’s wonderful quote: “I can paint you the skin of Venus with mud, provided you let me surround it as I will.”

While this principle is visible to the trained eye, both in painting and in life, it is never made more clear than in deliberately created optical illusions, like the e-Chalk color perception illusion I wrote about in this post.

This image shown here is one of the most striking illustrations of this principle I’ve seen.

I came across it in a post by Phil Plait on Bad Astronomy, who indicated the the original is from Akiyoshi Kitaoka’s optical illusion website (scroll to the bottom of the page).

Anyone with normal color vision will see a series of green and blue spirals. There would be little chance that a casual observer would suggest that the blue and green might be the same color, and yet they are.

You can see in the first detail image that the “green” spirals are only crossed by bands of orange, and the “blue” spirals are only crossed by bands of magenta.

In the second detail, you can see the Photoshop foreground/background color blocks where I have used the Eyedropper tool to pick one color out of the “green” band, and the other out of the “blue” band.

They are identical RGB values, 0, 255, 150. The same color.

The color is actually a green leaning toward blue. Richard Wiseman used Photoshop to change all of the values except the green and blue bands to black, and you can see a detail of the result in the bottom image. There is also a simplified version of the illusion here.

So the next time you’re looking at a color an think “that’s green” or “that’s blue”, well, maybe it is, maybe it isn’t, depending on the surrounding colors.

The FM 100 Hue Test is a seemingly simple test of your ability to discern close hue relationships, a sort of “color IQ test”.

The interactive is provided by x-rite, a company that makes Munsell-based color measurement products.

It consists of four bands of small squares of varying colors. Each band represents a scale of colors between two specific hues, represented by fixed squares at either end.

The task is to rearrange the drag-and-drop squares within each row to set them in the appropriate order of hue.

When you get down to the fine discrimination between hues that are very close, it becomes harder than it seems at first.

You get a score at the end, “0″ being perfect, and the opportunity to compare your score to others of your gender and age group. There is also a feature, that I was unable to take advantage of because I came up with a perfect score, that allows you to see the color ranges within which you had the most difficulty discerning the close hue relationships.

Scorekeeping and the game-like element aside, this is an enlightening exercise in comparing closely related hues, something of concern to anyone working in color, particularly painters looking to match the colors they see when mixing paint.

One of the keys that helped me with the exercise was not being shy about moving closely related colors side to side after they were in position, making it a bit easier to compare them briefly in a different context. Many of the color squares, arranged in their correct relationship, can appear identical until you shift them one position to the right or left. That in itself is an interesting phenomenon.

As always when viewing or judging color, whether in isolation, on a palette, in a digital color picker or in a painting, the important factor is the relationship of a color to its adjacent colors.

Have fun.

[Via Art School at Home, via Making a Mark]

It’s been the subject of much discussion, some suggesting that it is misleading enough that it should be rethought entirely, but the color wheel remains the most common and convenient method for visually understanding and comparing the relationships of different hues.

As part of the Gutenberg-e project by the American Historical Association and Columbia University Press, Sarah Lowengard has written a scholarly treatise on The Creation of Color in Eighteenth-Century Europe, the third chapter of which, Number Order, Form, delves into the history of color wheels and other visual systems of ordering and visualizing the relationships of colors.

The link going around the web currently (I found it on Digg) is to a post on the Color Lovers blog, which has extracted selections from her paper into an article on the History of the Color Wheel.

Color circles have been used to describe associations of colors from medieval times, but the first known example of the representation of hue in the form of a wheel, or circle, commonly suggested as the original color wheel, is traced to Sir Isaac Newton; whose keen mind was for some time focused on the nature of light and color.

Other systematic visual arrangements of colors precede it, like Tobias Mayer’s Trhchromatic Graph [correction - see below], which he first described in 1758 (interpreted by Georg Christoph Lichtenberg, image above, top left), but Newton’s circle is recognizable as the predecessor of the one in modern art texts. (For a couple of color wheels that I find particularly useful, see my links to Bruce MacEvoy’s artist pigment color wheels on handprint at the end of this article.)

Newton’s experimentation splitting sunlight with a prism is relatively well-known. (It’s still a fun and instructive practice is you haven’t indulged in it, I got mine from Edmund Scientific.)

Less well known is Newton’s original color circle, or hue circle, which was actually a kind of pie-chart (image above, top right), in which the bands of color he observed were distributed in wedges corresponding to their width in the observed spectrum, and arranged around the circle in the order of their wavelength. Newton emphasized that his circle represented the properties of the color of light (additive color), not artists’ pigments (subtractive color).

It was Newton who accomplished something that I have long been fascinated with, and confused by — the “closing of the circle”.

Physical wavelengths of light, which our eyes and brains interpret as different hues, can be thought of a part of a linear arrangement, segments of the electromagnetic spectrum; a continuous band of wavelengths of energy from the very short (X-rays and Gamma rays), with wavelengths measured in the distances equivalent to atomic nuclei, to the very long (radio waves) with wavelengths measured in distances on a human scale (meters or 10’s of meters).

The spectrum of visible light sits somewhere in between, at wavelengths the size of protozoa (micrometers, or millionths of a meter, also known as microns), ranging from red on the short end at 700nm, to violet on the long end at 400nm.

But how, my fevered little brain would like to know, does this linear relationship bend back on itself, like the optical equivalent of a Möebius strip, and connect in a continuous band; and how does it fit into that neat and oh-so-convenient system of primary, secondary and tertiary colors, triads; and in particular, the dramatic, and apparently biologically founded, relationship of color wheel opposites, or complementary colors?

This seems to have something to do with a “gap” in the color wheel, between the physical wavelengths of red and violet, in which the purples fill in with colors that are not discrete frequencies on the spectrum, but combinations of others.

I have to admit that I’m still basically unclear about this, but let’s face it, we always knew purple was weird.

Correction and addendum: Divid Briggs, author of The Dimensions of Color, was kind enough to write a comment and point out that though many systems of color charts precede Newton, Mayer’s was not one of them.

He also appears to have an answer to my question about the “closing of the circle”, which comes from the opponent model of vision. He explains if briefly in his comment on this post, and in more detail on The Dimensions of Color.

It turns out that I’m obliquely familiar with this model of human vision, which is based on two “channels” or scales of color, redness vs greenness and yellowness vs blueness, and a lightness scale or channel, in that this is the color model on which the LAB (CIELAB) color space is modeled.

CIELAB (”LAB color”) is a color space used in Photoshop, and is the fundamental color space on which Photoshop bases its interpretations of other color spaces. If you convert between CMYK and RGB, for example, Photoshop converts to the first color space to LAB and then from LAB to the other. (Here’s Adobe’s Technote.)

The CIELAB color space, based in part on Munsell but founded on the biological way in which the cones in the eye react to color, was codified in 1931 by the Commission Internationale d’Eclairage (International Commission on Illumination) to describe all colors visible to the human eye.

The closed circle of the color wheel is a product of the related opponent model of vision in which the interaction of the redness to greenness and blueness to yellowness scales forms a circle, and the oppositions produce the famous complementary color effects with which artists are so familiar.

So there’s my answer. It’s in the eye of the beholder.

Peter Max rose to fame at a pop artist and poster artist associated with the mass media image of the 1960’s psychedelic art movement.

Max took his influences from the underground psychedelic concert posters and album art of the time, and the graphically simplified echoes of that art pioneered by Heinz Edelmann and Milton Glaser, and refined them into a cheerful, less threatening version that became wildly popular.

Max applied his version of the style to a line of very successful silkscreen posters posters and moved it into advertising design, clothing, and various kinds of marketing and product design, even to busses, large scale murals and the painted fuselage of one of Continental Airline’s Boeing 777’s.

His work became synonymous with 60’s “psychedelic art”, though to my mind he was less of an innovator than people like Stanley Mouse, Victor Moscoso, Rick Griffin, Wes Wilson and Anton Kelly. Fame wins out, however, and Max’s psychedelic lite version became a pop culture icon while the originators faded into obscurity. (I’ll do my best to introduce you to them in future posts.) Heinz Edelmann carried his style into the design for the influential animated feature Yellow Submarine, which is often wrongly attributed to Max.

The path of influences is difficult to sort out, however, and you can see the influence of Max and his progenitors and contemporaries on modern retro-60’s style, European comics artists like Moebius and Bati, and album cover art through the intervening years.

If my tone makes you think I don’t appreciate Peter Max, I’m remiss, because I actually do like him when he’s at his art-deco kaleidoscopic best, I just lament the obscurity of other artists who pioneered this style.

Max himself moved his style into a kind of neo-expressionism, often mixed with the pop psychedelia of his poster art. He expanded his working methods into a number of media and remains active today, creating posters, magazine covers, limited edition prints and gallery paintings.

His work is full of the vibrantly intense color relationships associated with psychedelic and op art, in which high-value, high-saturation colors are frequently juxtaposed with their compliments, causing an increased intensity and optical “vibration” from the way the brain processes color.

His web site has a small selection of his 60’s work. The gallery is the “Shop” (which tells you something), look in the “Vintage Poster” section. There are also interesting works in the contemporary “Posters”, particularly under “Misc.” I can’t give you direct links because the site is in frames.

A collection of his work, The Art of Peter Max, was published in 2002.

There is an exhibition called Peter Max and the Summer of Love at the de Young museum in San Francisco from now till October 28, 2007, supposedly in celebration of the 40th anniversary of the “Summer of Love” in 1967.

I’m not exactly sure what Peter Max actually has to do with the “Summer of Love”, except that they both marked the explosion of the 60’s counterculture into mainstream culture, which was, of course, its death knell. The establishment brownshoes who got so uptight at the rise of the “dirty hippies” who wanted to subvert the authoritarian consumerist conformity they desperately wanted to maintain just didn’t have enough faith in American Popular Culture, which, like a cosmic game of Katamari Damacy, can absorb anything.

Far out, man.

[Exhibition listing via Art Knowledge News, photo of Peter Max mural on Atlantic City boardwalk (image top, enlargement here) from Flickr set by iirraa, I've taken the liberty of cropping it and adjusting levels. Note the size of the passer-by on the boardwalk.]

Sergei Bongart was a Russian painter who was born in the Ukraine, studied at the Russian Academy of Arts in Kiev, and went on to paint and study in Prague, Vienna and Munich. He emigrated to the U.S. in the middle of the 20th Century, lived, painted and taught in Idaho and then in California, where he established the Sergei Bongart School of Art and administered it for many years.

He is admired for his richly colored and emotionally expressive landscapes, still lifes and portraits. He was best known as a colorist, working in exaggerated color, using dynamic but carefully controlled color relationships and extolling the virtues of approaching painting as “color first, subject last”.

There is a book, Sergei Bongart by Mary N. Balcomb, that you can read excerpts of here and find more information about on Balcomb’s site.

Bongart’s approach looks like an intersection between Russian impressionist style painting (see my previous posts on Russian galleries in the U.S. here and here) and Cézanne’s oblique path into the distillations of modernism. Bongart’s brusquely applied strokes of vibrant color create representational images, but you can tell that it is not the objects but color itself that is the subject of his paintings.

Link via Art Notes – Interesting Art Stuff

Here are a couple of interesting diversions that dramatically illustrate the degree to which color perception is controlled by the effect of previous or adjacent colors.

The first, Big Spanish Castle, is a simple, but dramatic and fun, color-based optical illusion. Based on the visual effects of complementary colors and the optical/brain phenomenon known as an afterimage, the illusion is similar to others in which these principles are used, as in the American Flag illusion on the Wikipedia page for afterimage.

In this case, however, the effect has been cleverly combined with a photograph for a fun and striking effect.

Go to the page linked here, and below, which is posted by graphic designer John Sadowski. There you will find a larger version of the image at top-left. Stare at the dot in the center of the image for 30 seconds (the one on the linked page, not the one here) and then, without moving your eyes, mouse over the image; and you will see what appears to be a color photograph. Once you move your eyes, however, you will find that the photograph is, in fact, black and white. Fascinating.

Sadowski gives links to instructions for creating your own version of the illusion (requires Photoshop), and a list of various versions of the illusion that people have sent in.

The second, which is one of three color perception demonstrations on e-Chalk (image at left, bottom), is one of the most dramatic examples I have seen of how adjacent colors affect the perception of the value and hue of a color.

Choose the “illusion 1″ button at the bottom of the page. The interface requires Flash (which you probably have) and allows you to move a dragable mask over the image, isolating two parts of it that look initially to be radically different colors, dark blue-gray and bright yellow, but are demonstrated to actually be the same color. The effect is quite dramatic. The other two experiments are similar in nature.

There is also a related image on the Wikipedia page for optical illusions that demonstrates the same principle, but with the value of a gray tone. It requires a bit more work on your part to view the proof but the effect is also striking.

All of them demonstrate that color, like beauty, is in the eye of the beholder.

handprint is the personal site of Bruce MacEvoy. The home page displays an unlabeled group of eight graphic symbols reflecting entry points to the sections of the site, which are a rather bizarre amalgam of his personal interests, from literary experiments to essays on Shakespeare’s Sonnets, human evolution and the philosopher Ludwig Wittgenstein.

One of the symbols is a simplified representation color wheel. Beneath this lies one of the most comprehensive and extensive painting resource sites on the web.

Starting with a guide to watercolor papers, moving on through brushes and paints. In each case the subjects are broken down into sub-sections dealing with history, manufacture, and the details of how to choose between the bewildering array of brands, styles and degrees of quality.

He then goes into selecting palettes, from simple to advanced arrays of colors, and detailed sections on color mixing, color theory and the use of various kinds of color wheels, including a nice one in which painters’ colors are arrayed on a color wheel so you can tell where, for example, venetian red sits relative to burnt sienna in terms of hue and intensity. (There is a larger, downloadable PDF version of this color wheel.)

There is even an extensive section on vision, optics and color perception. His section on techniques not only includes watercolor specific techniques like laying a wash and preparing watercolor papers, but other skills like basic perspective and modeling forms with value and color. Some sections, techniques in particular, are still under development as indicated by names of future topics that are not currently linked.

There is also a section on books, once again extensive, in which MacEvoy reviews and recommends titles on a variety of topics, from learning the basics to advanced color theory. In addition he lists and reviews major art retailers.

Ths site also contains some examples of MacEvoy’s own recent work, which is anything but showcased, you actually have to dig a bit to find it. His style seems as inquisitively eclectic as the topics on the home page of the handprint site, and features some figure painting, portraits and plein air landscapes that are very appealing.

MacEvoy has also posted a journal of thoughts and observations on painting that would make a web site in itself, as would many of the sections and sub-sections of this surprisingly deep site.

As if all of this weren’t enough, under the modest link “artists” is a wonderful section of illustrated essays on dozens of watercolor artists, from botanical and topographical illustrators to greats like Constable, Eakins, Homer and Sargent. Wow.

The site is an amazing resource, unfortunately marred by a less than ideal navigation system and his bizarre decision (what was he thinking?!) to center his columns of text, rendering them unnecessarily difficult to read. (Fortunately this practice isn’t carried to all pages, but it’s prevalent enough to be annoying.)

Don’t let that give you a moment’s pause, though. Anyone with any interest at all in watercolor, color theory, color mixing, vision, artist materials and techniques should check out the watercolors and watercolor painting section of handprint.

Part of the WellStyled.com web design workshop, the functionality of this color scheme generator is primarily aimed at web designers, but this is fascinating and fun for anyone who likes to immerse themselves in color and color relationships.

Click on the color wheel to choose a hue, choose a scheme (Contrast, Triad, Tetrad, etc) below that, and then click on the small rectangles in the color spaces to bring up a value/saturation picker. There are some other variations at the bottom of the main panel.

Any time you arrive at a scheme you like, click on “URL of this scheme” to bookmark the settings. There is even a dropdown menu for previewing how your scheme would look to people with varying types of colorblindness. For more info and instructions, see the Help page.